This invention generally relates to a rotating connector and, more particularly, to a rotating connector for use in a steering device for a vehicle, for instance, or like rotating connector for electrically connecting an inner cylinder side (a steering shaft side) and an outer cylinder side (a column side) which are combined together to permit the relative rotation in a substantially concentric state.
A rotating connector of this kind is composed of an inner cylinder and an outer cylinder which are combined together to permit the relative rotation in a substantially concentric state, and a flat cable which is housed spirally in an annular space formed by the inner cylinder and the outer cylinder and is connected at its inner end to the inner cylinder while being connected at its outer end to the outer cylinder.
In such a rotating connector, when the inner cylinder is rotated to unroll the spirally-rolled flat cable on condition that the outer cylinder is fixed in position, for instance, the flat cable makes the biased movement toward the outer cylinder resulting from the expansion of a roll diameter of the flat cable, or alternatively, when the inner cylinder is rotated in the reverse direction, the flat cable makes the biased movement toward the inner cylinder resulting from the reduction of the roll diameter. Thus, the inner cylinder and the outer cylinder are made relatively rotatable within the range from the position of the flat cable maximally biased toward the inner cylinder to the position of the flat cable maximally biased toward the outer cylinder.
As shown in FIG. 11, a flat cable 1a heretofore used in the rotating connector of this kind has been formed by coating sheet-shaped flat-type conductors 10a placed in parallel arrangement with an insulating film 11a consisting of a polyethylene terephthalate film through an adhesive resin layer 11b such as a saturated polyester copolymer, for instance.
The flat cable 1a is continuously manufactured as shown in FIG. 12, for instance, according to the steps of feeding the insulating films 11a, 11a respectively having the adhesive resin layers 11b on the inside by means of delivery rolls 51, 51, while feeding the foiled flat-type conductors 10a in the state of parallel arrangement by means of a bobbin 50, and then thermally bonding the insulating films 11a, 11a to the flat-type conductors 10a under pressure by means of heated machine rolls 5, 5, and the manufactured flat cable 1a is rolled round a take-up drum 52 in sequence.
The flat cable 1a rolled round the take-up drum 52 is cut in a predetermined length and is then incorporated into the housing as described above in the rotating connector.
Owing to the use of the flat cable 1a as described above, the rotating connector in the prior art has such disadvantages in that the adhesive resin layer 11b is forced out from a cut end surface of the flat cable 1a particularly in the high-temperature environment to prevent the rotation of the inner cylinder relative to the outer cylinder (an increase in torque occurs to make the rotation impossible in the worst case), and besides, softening of the adhesive resin layer 11b occurs to degrade the durability.
Further, the flat cable 1a makes the movement to enlarge a roll (i.e., to expand the roll diameter) or to narrow the roll (i.e., to reduce the roll diameter) in accordance with the rotation of the inner cylinder, for instance, while the opposite widthwise ends of the flat cable 1 are formed in an angular shape, and therefore, friction between the opposite widthwise ends of the flat cable 1a and the inner wall surface of the space causes large rotational noise at the time of rotating the inner cylinder.
It is an object of the present invention to provide a rotating connector which permits the smooth rotation of an inner cylinder or an outer cylinder even in the high-temperature environment and is excellent in durability.
Another object of the present invention is to provide a rotating connector which permits less rotational noise caused by a friction between the opposite widthwise ends of a flat cable and an inner wall surface of a space at the time of rotating the inner cylinder or the outer cylinder.
For attaining the above objects, a rotating connector according to the present invention has the following structure.
That is, a rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the fist mode of the present invention comprises an inner cylinder 2 and an outer cylinder 3 combined together to permit the relative rotation in a concentric state, and a flat cable 1 spirally housed in an annular space 20 formed between the inner cylinder 2 and the outer cylinder 3, and connected at its inner end to the inner cylinder 2 while being connected at its outer end to the outer cylinder 3, wherein the flat cable 1 is composed of a plurality of flat-type conductors 10 placed in parallel arrangement and an insulating coat layer 11 placed over the flat-type conductors 10, and the insulating coat layer 11 is formed by coating the flat-type conductors 10 with a thermoplastic resin by means of direct extrusion.
A rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the second mode of the present invention comprises an inner cylinder 2 and an outer cylinder 3 combined together to permit the relative rotation in a concentric state, and a flat cable 1 spirally housed in an annular space 20 formed between the inner cylinder 2 and the outer cylinder 3 in the mode of forming a portion of the flat cable into an U turn-shaped reversing part 12, and connected at its inner end to the inner cylinder 2 while being connected at its outer end to the outer cylinder 3, wherein the flat cable 1 is composed of a plurality of flat-type conductors 10 placed in parallel arrangement and an insulating coat layer 11 placed over the flat-type conductors 10, and the insulating coat layer 11 is formed by coating the flat-type conductors 10 with a thermoplastic resin by means of direct extrusion.
A rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the third mode of the present invention comprises an inner cylinder 2 and an outer cylinder 3 combined together to permit the relative rotation in a concentric state, a flat cable 1 spirally housed in an annular space 20 formed between the inner cylinder 2 and the outer cylinder 3 in the mode of forming a portion of the flat cable into an U turn-shaped reversing part 12, and connected at its inner end to the inner cylinder 2 while being connected at its outer end to the outer cylinder 3, and at least one flat dummy cable 6 spirally housed in the space 20 to be rolled in parallel to the flat cable 1 in the mode of forming a portion of the flat dummy cable into an U turn-shaped reversing part 6, and connected at its inner end to the inner cylinder 2 while being connected at its outer end to the outer cylinder 3, wherein the flat cable 1 is composed of a plurality of flat-type conductors 10 placed in parallel arrangement and an insulating coat layer 11 placed over the flat-type conductors 10, and the insulating coat layer 11 is formed by coating the flat-type conductors 10 with a thermoplastic resin by means of direct extrusion.
A rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the fourth mode of the present invention comprises an inner cylinder 2 and an outer cylinder 3 combined together to permit the relative rotation in a concentric state, a flat cable 1 spirally housed in an annular space 20 formed between the inner cylinder 2 and the outer cylinder 3 in the mode of forming a portion of the flat cable into an U turn-shaped reversing part 12, and connected at its inner end to the inner cylinder 2 while being connected at its outer end to the outer cylinder 3, and a plurality of rollers 7 provided within the space 20 so as to be located between an outer portion of the U turn-shaped reversing part 12 of the flat cable 1 and an inner portion of the U turn-shaped reversing part 12 thereof, wherein the flat cable 1 is composed of a plurality of flat-type conductors 10 placed in parallel arrangement and an insulating coat layer 11 placed over the flat-type conductors 10, and the insulating coat layer 11 is formed by coating the flat-type conductors 10 with a thermoplastic resin by means of direct extrusion.
A rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the fifth mode of the present invention is characterized in that the opposite widthwise ends of the flat cable 1 in the rotating connector according to any one of the first to fourth modes described above are formed in the shape of a circular arc in section.
A rotating connector with improved capability to withstand repeated alternating rotation in forward and reverse rotating directions according to the sixth mode of the present invention is characterized in that the thermoplastic resin for the formation of the insulating coat layer 11 includes a polyamide resin.